They are defined by parameters, namely height, base and perpendicular. The standard angles for which trigonometric ratios can be easily determined are 0 degree, 30 degree, 45 degree, 60 degree and 90 degree. Let's see the values of trigonometric ratios for angles 0 degree, 30 degree, 45 degree, 60 degree and 90 degree. The values are determined using the properties of triangles. The two acute angles of a right-angled triangle are complementary. From the table observation that as angle A increases from 0 degree to 90 degree, sin A increases from 0 to 1 and cos A decreases from 1 to 0. A pattern to help you remember the Sine and Cosines of Special Angles in the first quadrant. 0, 30, 45, 60, 90 degrees. How to evaluate trig functions of special angles? Easy way to use right triangle and label sides to find sin, cos, tan, cot, cosec, and sec of the special angles, and angles at multiples of 90 degree. The concepts covering Trigonometric Ratios of 45 degree, Trigonometric Ratios of 60 degree and 30 degree, T-Ratios of 60 degree, T-Ratios of 30 degree, Axioms For T-Ratios of 0 degree and Axioms For T-Ratios of 90 degree are explained very well via examples.